Thread cutting device for sewing machine

Abstract

The invention relates to a thread cutting device for a sewing machine. The thread cutting device includes: a cutting knife including a cutting edge and serving to carry out a rotation to an initial position and a thread cutting position advanced from the initial position to a stitch point side; a moving knife rotated to the initial position, a thread catching position advanced from the initial position and the thread cutting position retreated from the thread catching position in order and serving to cut a bobbin thread and a needle thread in cooperation with the cutting knife in the thread cutting position; and a clamp member for interposing and holding the bobbin thread between the clamp member and the moving knife by an elastic force applied through an elastic deformation, the clamp member including a first interposing portion for interposing the bobbin thread between the first interposing portion and the moving knife when the moving knife is returned from the thread cutting position to the initial position. The moving knife includes a catching portion for catching the bobbin thread in the thread catching position. The clamp member includes a second interposing portion for interposing the bobbin thread in abutment on a first abutting portion provided on a tip side of the moving knife from the catching portion when the moving knife is placed in the thread cutting position. The bobbin thread interposed by the second interposing portion in the thread cutting position is transferred to the first interposing portion and is held by the first interposing portion with a movement of the moving knife to the initial position.

Description

technical field [0001] The invention relates to a thread cutting device of a sewing machine. Background technique [0002] For example, as described in Patent Document 1, there is known a thread cutting device for a sewing machine that has a cutting knife that has a blade portion and is rotatably supported on a hub shaft stand (frame) to The initial position and the thread cutting position moving forward from the initial position to the needle drop position side; the movable cutter, which rotates on the kettle shaft table, moves sequentially to the initial position, the thread catching position advancing from the initial position, and the thread catching position The position is moved compared with the retreated thread cutting position, and the suture is cut through the coordinated action of the thread cutting position and the cutting knife; and the clamping part, which is fixed on the kettle shaft table (frame), utilizes the elastic force of elastic deformation , clamp and...

AI Technical Summary

Problems solved by technology

[0008] In order to solve this problem, it is also considered to prevent the pulling out of the lower thread by adjusting the length of the thread hooking part, that is, the length of the two slits. However, when the lower thread used in sewing is changed every time, it must be replaced. Since parts are clamped, there is a problem that the number of parts increases and work efficiency decreases

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